1. Field of the Invention
The invention relates to manually operable keyswitches in general, and in particular to pads, rows or banks of such keyswitches wherein the individual keyswitches are interlocked or interconnected so that only one keyswitch at a time is actuable.
2. Description of the Prior Art
It has long been the practice in the prior art to interconnect keyswitches in a pad or bank by providing complex mechanical interlocks between the keyswitches so that all are released when one keyswitch is depressed. These arrangements have suffered from problems of complexity, unreliability and high cost.
It has been proposed in at least two instances to interconnect switching or switch-like functions by a fluid filled receptacle. U.S. Pat. No. 2,800,034 describes a mechanical interlock between a relay, a contactor and a solenoid that includes a hollow member filled with liquid. U.S. Pat. No. 3,268,673 discloses a hydraulic pushbutton assembly in which a plurality of pushbuttons press on a common fluid filled bag.